反相微乳液碳吸附耦合法制备氧化钇稳定四方氧化锆纳米粉体及表征

采用反相微乳液和碳吸附法制备了氧化钇稳定四方氧化锆纳米粉体,探讨了碳黑的加入量对粉体比表面积的影响,得到最佳的碳黑量。分别采用XRD、TEM、BET和TG分析了不同温度下煅烧所得粉体的物相、颗粒度和比表面积以及前驱体热分解特性。实验结果表明,经700℃焙烧后制得了分散性好的四方相ZrO2纳米粉体,比表面积为97.4m2/g,平均粒径为9nm。     

微乳液和碳吸附耦合法制备氧化钐、氧化钆掺杂氧化铈纳米粉体及其电性能的研究

用微乳液和碳吸附耦合法制备了氧化钐、氧化钆二元稀土掺杂氧化铈纳米粉体(Sm2O3)0.08(G d2O3)0.02(C eO2-δ)0.8。探讨了碳黑的加入量对粉体表面积的影响,得到最佳的碳黑加入量。利用XRD、TEM和BET方法对其物相、分散性、颗粒形貌和比表面积等性能进行了表征。结果表明:700℃焙烧的粉体呈现良好的结晶状态,为立方萤石结构,比表面积为65m2/g,平均颗粒直径为12nm,分散良好。利用交流阻抗法测试了材料的电导率。结果表明,电导率随烧结温度的升高而增大。     

低温燃烧法合成掺钙铬酸镧粉体的工艺优化

通过正交试验,确定了用柠檬酸-硝酸盐体系制备有机前驱体,低温燃烧法合成掺钙铬酸镧粉体的优化工艺参数,讨论了粉体煅烧温度、柠檬酸量、溶胶pH值、乙二醇量、溶胶陈化时间和掺钙量对粉体BET比表面积的影响.结果表明,影响粉体BET比表面积的因素主次顺序为煅烧温度、柠檬酸量、pH值、乙二醇量、陈化时间、掺钙量.采用优化工艺制备粉体的BET比表面积为18.2m2/g.     

CeO2纳米粉体的一步熔融法制备及表征

采用熔盐法制备了氧化铈纳米粉体,探讨了改变铈与熔融盐之间的比例和烧结温度对粉体粒度的影响,确定了可控粉体的最佳实验条件.通过TG-DTA、XRD、TEM、BET等测试方法对其物相、颗粒度、分散性、颗粒形貌和比表面积等性能进行了表征.结果表明,烧结温度为400℃、熔融盐与铈比为3∶1时,制备出分散性好、呈良好的结晶状态的类球状纳米晶粒,比表面积为84.9 m2·g-1,平均粒径为10.7nm;随着烧结温度的升高,粉体的粒径逐渐增大,当烧结温度为600℃时,粒径为26nm.     

熔融法氧化钇纳米粉体的制备及表征

采用熔盐法制备了氧化钇纳米粉体,探讨了改变钇盐与熔融盐的比例和焙烧温度对粉体粒度的影响,确定了纳米粉体的最佳实验条件.借助TG-DTA、XRD、TEM、BET等测试方法,对其物相、颗粒度、分散性和比表面积以及前驱体热分解特性作了描述.结果表明,焙烧温度为500℃、熔融盐与钇盐比为4:1时,可制备出分散性好、比表面积为84.2m2/g 、平均粒径为11nm的氧化钇粉体;随着焙烧温度的升高,粉体的粒径逐渐增大.     

大颗粒LSM的制备及表征

采用共沉淀法制备了固体氧化物燃料电池的阴极材料LSM(La0.8Sr0.2Mn03).利用XRD、粒度分析仪、BET、SEM测试手段分析灼烧温度对所得粉体的晶相组成、颗粒粒度、比表面积及粉体形貌的影响.研究结果表明,随着灼烧温度的升高,形成的钙钛矿型结构渐趋完整,粉体的粒度逐渐增大,比表面积逐渐减小,其中心粒径都在30μm以上.     

共沉淀法制备Nd:YAG纳米粉体及其表征

采用共沉淀法制备出尺寸小、团聚程度轻、单分散、貌似球形的Nd:YAG纳米粉体.借助IR、XRD、BET、SEM和荧光分析仪等测试手段对前驱体和Nd:YAG粉体进行了表征与分析.结果表明,共沉淀温度及煅烧温度对产物的物相有较大影响;在聚乙二醇存在的情况下, 900℃煅烧前驱体2h得到单分散纯相的Nd:YAG粉体,粉体颗粒尺寸为30nm左右,比表面积为40m2·g-1左右;激活离子Nd3+的存在使粉体具有较好的荧光性.     

机械力促进低温快速反应的研究

研究了机械力作用下铁矿粉与碳粉的物理化学性能的变化规律.在球磨过程中,铁矿粉与碳粉的颗粒度及晶粒不断细化、比表面积不断增大,随着作用时间的延长,粉体会无定形化,甚至发生相变.在晶粒细化过程中,晶粒发生畸变和位错,形成了许多活化中心,这样就可以显著降低反应活化能,同时由于粉体比表面积的不断增加,极大改善了粉体的化学反应性能,促进了气固反应和固固反应,与传统粗粉体相比,氧化铁的还原温度下降300℃左右.采用催化剂和机械力共同作用,会更加明显降低碳还原铁矿粉、气基还原铁矿粉的反应温度.     

煅烧预处理对胶态成型用BeO粉体性能的影响

获得低粘度、高固相体积分数粉体悬浮液是陶瓷胶态成型的前提条件。为了提高BeO粉体悬浮液的固相体积分数,采用煅烧手段预处理粉体,研究煅烧温度(1 200～1500℃)和煅烧时间(1～4 h)对BeO粉体粒度、比表面积和烧结活性的影响规律,并研究相同固相体积分数(40%)条件下,煅烧对BeO悬浮液粘度的影响。结果表明:在煅烧过程中,粉体颗粒发生长大,比表面积和烧结活性均降低,温度的影响明显大于时间,且煅烧时间低于2h时影响不大,煅烧温度高于1 300℃后粉体相关性能大幅下降;煅烧降低粉体比表面积,除去表面的水分等吸附物质,改善BeO粉体的表面性质,因此在相同固相体积分数(40%)条件下,粉体悬浮液的流动性能得到改善,从而煅烧可提高悬浮液的固相体积分数。     

碳酸氢铵沉淀法制备大颗粒球形氧化钇的研究

采用碳酸氢铵沉淀法制备球形大颗粒氧化钇粉体,粉体用激光粒度仪、SEM和BET分析方法进行表征,研究了反应温度、料液浓度、陈化时间、灼烧温度对氧化钇形貌、粒度、比表面积的影响。最佳的工艺条件为:沉淀反应温度93℃、料液浓度40 g/L、陈化时间28 h、灼烧温度1400℃,在此条件下制备出氧化钇,中心粒径D50为61.54μm,形貌为针状晶体组成的球形。     

转炉炉壳热应力分析

根据实际转炉建立实体模型。以有限元为手段,考虑了炉衬和炉壳材料的物性参数随温度变化的特点和炉衬与炉壳之间膨胀间隙,计算了转炉炉壳在温度载荷和炉衬膨胀压力同时作用下的热应力。所得结果可为转炉炉壳设计提供依据。     

焦炭热性能指标意义浅析

通过对焦炭在高炉内的历程及其变化规律的剖析,阐述焦炭热性能指标的意义,形象地把焦炭在高炉内的损耗分为三部分(M1,M2,M3)。指出M2对焦比及焦炭价格有一定的指导作用。     

Results of treatment of cancer of the cardia

Cancer of the cardia is traditionally discussed with cardiac cancer of the lower portion of the esophagus and upper gastric cancer invading the esophagus, and the specific characteristics of cancer of the cardia have never been clearly defined. We reviewed the outcome of 172 patients with adenocarcinoma of the cardia who had undergone radical surgery between 1949 and 1994 in the Division of Gastrointestinal Surgery of the Cancer Institute Hospital. The centers of the tumors were located within 2 cm above and below the boundary between the esophagus and the stomach, and their longitudinal diameter was less than 8 cm. We divided the patients into an early period (1949-1979; n = 79) and a late period (1980-1994; n = 93), and focused on the historical transition. There were no differences in patient gender or histology between the two periods. However, the late period was associated with fewer cases of esophageal invasion and shorter longitudinal diameter, as the age of the population advanced. The number of advanced cancers such as the localized and infiltrative type had decreased, and early cancer and early clinical stage had become more common, but despite the fact that the number of early cancers had increased, extended dissection, such as thoracic and paraaortic lymph node dissection, was performed more frequently. By clinical stage, the long-term outcome markedly improved in Stage I patient in the late period, and tended to improve in Stage II and III patients. This appears to have been attributable to the prevention of micrometastasis by extended dissection, although the number of early cancers is another major potential cause. There were no differences in the outcome of Stage IV patients between the two periods, and further advances in multimodality therapy must be awaited. The range of resection is basically proximal gastrectomy, and if there are adequate indications, the prognosis is favorable. In view of the status of lymphatic flow and lymph node metastasis, and long-term results, lateroaortic lymph node dissection is important. Since the number of early cancer patients has been increasing, if intraabdominal recurrence is prevented, intrathoracic lymph node dissection will contribute greatly to the outcome of such patients.     

The effect of amount of possession of the trait of hostility on accuracy of perception of hostility in others.

Some theories of personality hold that an individual's perception of others is influenced by his own personality characteristics; more specifically, that a trait of low social value will be projected more into others, and that insight into the possession of these characteristics reduces this distortion. These 2 hypotheses were tested by having a group of college students rate each other (including themselves) on degree of friendliness or hostility. Agreement with group rating about self yielded the insight score. In general, the hypotheses were supported; the "friendly" Ss were most accurate in their perception of others, and insight was positively associated with accurate perception. From Psyc Abstracts 36:04:4HL16M. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Comparison of rates of infection of two methods of emergency ventricular drainage

The rates of infection of two methods of external ventricular drainage in use at Atkinson Morley's Hospital--namely, (a) percutaneous drainage with Rickham reservoirs and (b) tunnelled ventriculostomies--were compared in this retrospective review. Percutaneous drainage of CSF with Rickham reservoirs was associated with a 27% rate of infection as identified by positive microbiological cultures; tunnelled ventriculostomy catheters had a 10% infection rate. The difference in the infection rate between the two methods was statistically significant (P < 0.015). Other variables examined, including the age and sex of the patients and the reasons for ventricular drainage, were not associated with an increased rate of infection. Most infections from either method were caused by a coagulase negative staphylococcus. The average duration of ventricular drainage before identification of positive cultures was 5.7 days for Rickham reservoirs and 6.0 days for ventriculostomies.     

浅析《野草》的版画特征

鲁迅先生一生热爱美术作品,对版画中木刻兴趣尤甚.<野草>作为其"写心之作",亦呈现出一些与木刻版画一致的审美特征:一是具有木刻版画的色彩特征,多对比、多冷色,有阴郁的美感;二是具有木刻版画的力度特征,环境描写、人物刻画处处刀锋毕现,遒劲有力,有一种"力之美".     

四辊破碎机车刀架的改造

针对四辊破碎机车刀架车削中存在的几个问题,详细介绍了电动车刀架的结构和工作原理,建立主要设计参数的数学表达式,并进行适当的分析。改造后,这种电动车刀架运行平稳、可靠、方便、省力,取得了预期的效果。     

Effect of antibiotics of chemotaxis of human leukocytes

The effect of 20 different antibiotics on chemotaxis by human neutrophils was studied. Human leukocytes incubated with chloramphenicol, rifampin, sodium fusidate, and tetracyclines in vitro showed markedly depressed migration. The mechanisms by which these antibiotics affect leukotaxis are discussed.